1. Field of the Invention
The present invention relates generally to methods of coding a signal for digital optical communication for use in electric home appliances and information equipment capable of infrared communication, and more particularly, to a method of coding a signal for digital optical communication, the spectrum of which attains a zero level at a prescribed frequency within a main lobe band, a baseband transmitter or an ASK transmitter using the method, and a baseband receiver or an ASK receiver decoding a signal coded by the method.
2. Description of the Related Art
Conventional digital optical coding methods are roughly divided into coding method using a subcarrier and coding methods without using a subcarrier. Herein, the subcarrier refers to a carrier wave artificially created by turning on/off light at a certain cycle. A rectangular wave of light simply turning on/off is often substituted for the subcarrier. A method of deforming the waveform of a signal for communication data by a prescribed rule for transmission without using the subcarrier is called a baseband coding method. Meanwhile, a method of transmitting communication data by changing any of a amplitude, phase and frequency of a subcarrier based on the data is called a carrier band coding method.